1. Field of the Invention
The present invention relates to antennas and, more particularly, to an antenna for mounting on the windshield for radio communication.
2. Description of the Related Art
Following the fast development of communication technology, a variety of mobile communication apparatus have been disclosed and commercialized. Further, regular automobiles commonly have an antenna for receiving radio signal.
FIG. 1 illustrates an antenna for use in an automobile. As illustrated, the antenna comprises an antenna terminal 5, a mounting base 6, and a transmission box 7. The antenna terminal 5 is a metal member having two mounting lugs 51 arranged in parallel at one end of the terminal body 50 thereof. Each mounting lugs 51 has a pivot hole 52 transversely aligned in a line. The mounting base 6 is comprised of a holder plate 60 and a connector 61. The holder plate 60 has a through hole 62. The connector 61 is made from metal, having a shaft 63 inserted through the through hole 62 of the holder plate 60 and a pivot hole 64 transversely extending through the distal end of the shaft 63 and aligned between the pivot holes 52 of the mounting lugs 51 of the antenna terminal 5. A screw bolt 53 is fastened to the pivot hole 64 of the shaft 63 and the pivot holes 52 of the mounting lugs 51 to pivotally secure the antenna terminal 5 to the holder plate 60 and the connector 61, enabling the antenna terminal 5 to be turned about the screw bolt 53 relative to the mounting base 6. A retainer ring 54 is mounted in one end of the terminal body 50 between the pivot holes 52 of the mounting lugs 51 around the threaded shank of the screw bolt 53 to hold the antenna terminal 5 in position and to allow the terminal body 50 to be turned about the screw bolt 53 by force. The transmission box 7 comprises a casing 70, a cover plate.71, a metal plate 72, and a transmission line 73. The casing 70 defines a receiving open chamber 74. The cover plate. 71 is fastened to the casing 70 to close the receiving open chamber 74, having a center wire hole 75. The metal plate 72 is located on one side of the cover plate 71 opposite the receiving open chamber 74. The transmission line 73 is received in the receiving open chamber 74, having one end inserted through the wire hole 75 and electrically connected to the metal plate 72. During installation, the mounting base 6 is mounted on the outer surface of the windshield outside the automobile, and the transmission box 7 is mounted on the inner-surface of the windshield inside the automobile opposite the mounting base 6, enabling signal to be transmitted between the transmission line 73 and the antenna terminal 5 through the connector 61 and the metal plate 72 via the windshield.
According to the aforesaid, antenna structure, the antenna terminal is pivotally fastened to the base by a screw bolt. When the automobile moves over an uneven road surface, the antenna terminal tends to vibrate and shift to a different angular position, resulting in reception failure or poor reception. When fastening the screw bolt, a screwdriver or like tool should be used. Further, the fabrication of the transmission box is complicated because a wire hole must be made in the cover plate for passing therethrough of the transmission line and the transmission line must be fastened to the metal plate by soldering when the same extends out of the cover plate through the wire hole.
for an automobile